Hydrocarbons are widely used as a primary source of energy, and have a significant impact on the world economy. Consequently, the discovery and efficient production of hydrocarbon resources is increasingly important. As relatively accessible hydrocarbon deposits are depleted, hydrocarbon prospecting and production has expanded to new regions that may be more difficult to reach and/or may pose new technological challenges. During typical operations, a borehole is drilled into the earth, whether on land or below the sea, to reach a reservoir containing hydrocarbons. Such hydrocarbons are typically in the form of oil, gas, or mixtures thereof which may then be brought to the surface through the borehole.
Well testing is often performed to help evaluate the possible production value of a reservoir. During well testing, a test well is drilled to produce a test flow of fluid from the reservoir. During the test flow, key parameters such as fluid pressure and fluid flow rate are monitored over a time period. The response of those parameters may be determined during various types of well tests, such as pressure drawdown, interference, reservoir limit tests, and other tests generally known by those skilled in the art. The data collected during well testing may be used to assess the economic viability of the reservoir. The costs associated with performing the testing operations are significant, however, and may exceed the cost of drilling the test well. Accordingly, testing operations should be performed as efficiently and economically as possible.
One common procedure during well testing operations is flaring a gas flow associated with the well effluent. Many types of burners and flares are known that can efficiently combust gas flows having relatively high colorific content (i.e., a relatively high percentage of methane) without producing significant smoke or fallout. That is because, with a high calorific content, a high velocity gas jet may thoroughly mix with minimal risk of blowing out the flame.
It is more difficult, however, to cleanly burn gas flows having low calorific content, also known as “lean gases.” Lean gas flows may have a relatively high proportion of inert gases, such as nitrogen, which dilute the flammable content of the gas and therefore increase the risk of quenching the flame. Other inert gases, such as carbon dioxide, do not simply dilute the gas but may also actively inhibit flame when present in certain concentrations, such as greater than 35% of the gas flow content. Even at concentrations less than 35%, the flame inhibiting inert gases such as carbon dioxide may significantly increase the risk of flame blow-off.
Various burner designs have been proposed for combusting gas having a low calorific content. In general, the proposed burners require complex gas flow paths that are susceptible to clogging, have complex designs that complicate construction and maintenance, and/or are otherwise unsuitable for flaring waste fuel during well testing operations.